body {
  margin: 0px;
}

.bg {
  width: 100vw;
  height: 100vh;
  background-size: cover;
  transition: background-image 1s;
}

.bg1 {
  background-image: url('../../images/batman01.jpg');
}
.bg2 {
  background-image: url('../../images/batman02.jpg');
}
.bg3 {
  background-image: url('../../images/batman03.jpg');
}
.bg4 {
  background-image: url('../../images/batman04.jpg');
}

/* #是id选择器 */
#spTime {
  background-color: rgba(0, 0, 0, 0.6);
  color: #fff;
}
